Uncache a LV when a cache PV is gone, bug ?

(I'm not on this list, so I can't properly followup to the thread in question, which is at
https://www.redhat.com/archives/linux-lvm/2015-August/msg00008.html
, but: )

I have a not-great-but-it'll-do workaround for the issue of trying
to un-cached an LV. It's at https://www.dropbox.com/sh/bvyy92wwoe8rcse/AADbgbklYGqrPoWUsLogmavha/computers/stripping_away_lvmcache.txt?dl=0

Just thought I'd share for future searchers.

-Robin